One of Victoria's oldest abattoirs, Riverside Meats Abattoir, has been sanctioned and four staff sacked over poor animal welfare, after secret video revealed mistreatment of animals.

More than 170 hours of vision secretly filmed inside the Echuca slaughterhouse is being looked at by PrimeSafe, the regulator overseeing abattoirs.

It is the second time in three years the regulator has taken action against the company.

Victoria's Chief Veterinary Officer has also been asked to look into animal cruelty allegations.

The vision was sent anonymously to animal rights group Animals Australia three weeks ago, who then passed it on to the authorities.

"It shows equipment designed to make processes more humane, instead being used as torture devices on the animals," Animals Australia's Glenys Oogjes said.

"There is an obvious culture of violence, disrespect and abuse of animals in this slaughterhouse.

"In one of the worst examples of abuse, a pig in a cattle restraint box suffered multiple shots from a captive bolt gun, then was shot twice with a rifle, the ordeal lasting over six minutes."

ABC has been given access to three-and-a-half minutes of the footage filmed at the abattoir.

Stunning procedure 'inadequate' and 'cruel'

PrimeSafe said it was an edited version of 170 hours of vision it was currently investigating.

"From our analysis, the video includes both recent and historical sections," PrimeSafe said in a statement.

The disturbing vision shows calves and sheep being stabbed in the neck, face and head with the metal prongs of an electric stunning device instead of on the side of their heads.

Some are stabbed repeatedly in the neck.

Chair of the Queensland Animal Welfare Advisory Board Professor Clive Phillips analysed the video and said some of the animals had not been adequately stunned.

"It shows animals which are experiencing pain and suffering which is the usual definition of cruelty" Professor Phillips said.

"The stunning procedure itself appears a rather unusual one of jabbing tongs into the side of the neck rather than electrocuting them either side of the brain."

Australia is a signatory to the World Animal Health Standards, which requires the electric pulse be administered to either side of the brain.

Smoke can also be seen coming from the animals as they are stunned and dairy calves and sheep can also be seen escaping from restraints falling onto the kill floor.

In a statement, Primesafe said a number of Australian standards have been breached and evidence was found of poor animal handling that was not best practice.

The same company was also recently fined more than $15,000 by Environment Protection Authority Victoria (EPA) for failing to manage offensive odours.

In 2013, a number of workers at the same abattoir were given warnings, the owners promised infrastructure and training upgrades, and the audit regime was increased after vision emerged of the mistreatment of dairy calves.

Animals Australia is calling on the Victorian Government to introduction CCTV cameras in all abattoirs and for footage to be independently monitored.

"If this is what's happening in an abattoir that should be under increased scrutiny, we can have no confidence whatsoever that similar abuses, or worse, are not happening in other slaughterhouses throughout Victoria," Ms Oogjes said.

"Once again we are seeing that wherever eyes aren't watching, animals are at risk of extreme cruelty."

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